1. Field of the Invention
This invention relates generally to arrangements and systems for balancing rotating machinery, and more particularly, to a system and apparatus which employs fluid mass for balancing rotating equipment, such as a grinding wheel.
2. Description of the Related Art
Numerous efforts have been made in the prior art to achieve a dynamic balance of a rotating machine part. In a number of such prior art efforts, a plurality of chambers are arranged on the rotating part, and fluid is injected into the chambers, in a respective quanta, to achieve the desired balance.
In some prior art arrangements, compensation for imbalance is effected by a mechanical system which employs compensating weights. The adjustment of the compensating weights is achieved, in one known system, by placing the weights in respective cylinders having circular cross-section, but their axis follow a circular line. Balancing is achieved during rotation of the machine part by moving the weights along their respective cylinders. Such motion is achieved by applying fluid pressures at opposite ends of each cylinder, whereby the weight is displaced along the curved cylinder in response to such fluid pressures. Clearly, this known system constitutes a complicated arrangement, which requires the production of complex curved cylindrical voids to be created within a portion of the machine.
In other known arrangements for achieving compensation for imbalance of a rotating machine part, heating or cooling means are employed to establish a temperature differential between respective ones of the balancing chambers which contain the mass fluid. In these known systems, a warmer chamber loses mass to a cooler chamber. This known type of balancing system involves complicated arrangements for providing energy to thermal devices in the chambers. Such thermal systems are inherently slow to respond and difficult to control in closed loop configurations. In some known systems, electromagnetic energy for energizing the thermal devices is transmitted across an air gap which separates stationary and rotating portions by means of selective energization of primary and secondary coils.
In still further known balancing arrangements, apertures associated with respective balancing chambers are provided on the spinning face of the machine part, and nozzles are located near the apertures, such that a fluid is squirted by the nozzles through the apertures and into the chambers needing the additional mass of the fluid to achieve a balanced state. A timing arrangement controls the operation of the nozzle. This known arrangement, however, is complicated in its implementation. Moreover, when the machine part is no longer rotated, the fluid flows out of drain holes which are associated with respective ones of the apertures. Thus, in addition to the complicated implementation, this known system suffers from the further disadvantage of releasing the fluid into the work area, causing rusting of the equipment and rendering difficult cleanup of the work area.
As is evident from the foregoing, a variety of problems exist in prior art systems. For example, the known fluid balancing systems squirt fluid after the machine element is rotating, and therefore do not provide correction for imbalance at the beginning of each start cycle. With respect to those known arrangements which require an injected liquid, the liquid generally will run out of a system each time rotation of the machine part is stopped. There is therefore a need for a fluid balancing system wherein the distribution of the balancing fluid in the respective balancing chambers remains intact as the machine element is stopped.
It is, therefore, an object of this invention to provide a system for balancing a rotating machine part without loss of the balancing, or mass, fluid into the work area.
It is another object of this invention to provide a system for balancing a rotating machine part without the need of complex machining to be performed on the rotating part.
It is also an object of this invention to provide a system for balancing a rotating machine part which is entirely closed to prevent contamination of the mass fluid as it is transferred into and out of the several balancing chambers.
It is a further object of this invention to provide a system for balancing a rotating machine part which does not require heating or cooling means for creating differential temperatures between adjacent balancing chambers on the rotating machine part.
It is additionally an object of this invention to provide a system for balancing a rotating machine part wherein the quantum of balancing fluid distributed amongst the balancing chambers is controlled.
It is yet a further object of this invention to provide a system for balancing a rotating machine part wherein the distribution of the balancing fluid amongst the balancing chambers will remain undisturbed when the rotating machine part is stopped and restarted.